JP4250468B2 - Magnetic resonance imaging system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a perpendicular magnetic field type magnetic resonance imaging apparatus (hereinafter referred to as an MRI apparatus) in which a static magnetic field direction is orthogonal to a body axis direction of a subject, and particularly to a technique for attaching a gradient magnetic field coil cable.
[0002]
[Prior art]
The MRI system uses the nuclear magnetic resonance phenomenon that occurs in the nuclei of the atoms that make up the subject when the subject placed in a uniform static magnetic field (imaging space) is irradiated with a high-frequency magnetic field. By detecting a magnetic resonance signal (hereinafter referred to as an NMR signal) and reconstructing an image using the NMR signal, a magnetic resonance image (hereinafter referred to as an MRI image) representing the physical properties of the subject is obtained. It is. In order to give this imaging position information, a gradient magnetic field is applied in a superimposed manner on the static magnetic field.
[0003]
In recent years, in a vertical magnetic field type MRI apparatus in which the direction of the static magnetic field is perpendicular to the body axis direction of the subject, a concave arrangement space is provided on the opposing surface of the coil container that is arranged to face the upper and lower sides, and the gradient magnetic field coil Has been proposed, and is desirable to reduce the required magnetomotive force (for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-99296
FIG. 3 (a) shows an example in which the gradient magnetic field coil cable is pulled out from the outer periphery of the gradient magnetic field generating coil and arranged on the imaging space side of the superconducting magnet in the vertical magnetic field type MRI apparatus described in Patent Document 1 above. .
In FIG. 3 (a), 101 and 102 are vertically opposed to each other, and a superconducting magnet having a space for placing a concave gradient magnetic field coil on the vertically opposed surface of the coil container (101 is the upper side, 102 is the lower side). , 501 and 502 are gradient magnetic field coils (501 is the upper side and 502 is the lower side) arranged vertically opposite to the concave arrangement space of the superconducting magnet (101 and 102), and 901 and 902 are the gradient magnetic field coils (501 and 502). Gradient coil cable (901 is the upper side, 902 is the lower side), 4 is the base for fixing the lower superconducting magnet 102 to the floor, 105 is the superconducting magnet (101, 102) A refrigerator 106 for cooling the inside of the magnet is a shield room for preventing external noise from entering the space where the MRI apparatus is installed.
[0006]
In FIG. 3 (a), the direction of the static magnetic field is the vertical direction, and the cable of the gradient magnetic field coil has a portion that is oriented in a direction perpendicular to the direction of the static magnetic field. Lorentz force works. Therefore, in the example of FIG. 3 (a), it is necessary to firmly fix the cable of the gradient magnetic field coil to the surface of the superconducting magnet that contacts the imaging space side.
[0007]
However, the wiring example of the gradient magnetic field coil shown in FIG. 3 (a) has the following problems. In other words, as shown in FIG. 3 (a), when the cable of the gradient magnetic field coil is passed through the surface of the superconducting magnet that is in contact with the imaging space, the cable through which a large current flows passes by the subject, adversely affecting the subject. Or the cable passes through the vicinity of the shooting space, and the shooting space becomes narrow. The subject is moved from outside on the top of the subject table, but if there is a cable, it may hinder the top. Therefore, it is not preferable to pass the cable of the gradient coil through the imaging space side of the superconducting magnet.
[0008]
Therefore, an example is considered in which a through-hole is provided in the center of the superconducting magnet as shown in FIG. 3 (b), and the cable of the gradient magnetic field coil is drawn through the through-hole to the surface on the side opposite to the imaging space of the superconducting magnet. It is done. In FIG. 3 (b), reference numerals 103 and 104 denote through holes (103 is the upper side and 104 is the lower side) provided in the central portion of the superconducting magnet (101, 102), and the gradient coil coils (901, 902) Are arranged in the through hole and on the surface opposite to the imaging space of the superconducting magnet.
[0009]
[Problems to be solved by the invention]
However, in the example of FIG. 3 (b), the space between the lower side of the superconducting magnet and the floor surface is a work space where a person enters and fixes the cable. Therefore, it is necessary to keep the space wide. For this purpose, the height of the base 4 must be increased. In this case, the height of the entire superconducting magnet is increased, and the imaging space and height are also increased. When the height of the imaging space is increased, the subject is placed in the increased imaging space, so that a sense of fear is felt, and access to the subject is difficult for doctors and engineers who handle the apparatus. Furthermore, when the height of the entire superconducting magnet is increased, the top of the superconducting magnet must have a high ceiling height in the shield room 106 in order to secure a space necessary for the maintenance work of the refrigerator 105. Depending on the situation, it may be necessary to modify the ceiling of the room. Therefore, in the actual apparatus, the height of the lower magnet from the floor surface is lowered. For this reason, it has the subject that the cable fixation of a gradient magnetic field coil is very difficult.
[0010]
An object of the present invention is to provide a vertical magnetic field type MRI apparatus capable of suitably arranging and fixing a cable for supplying a current to a lower gradient magnetic field coil in a narrow space under a magnet. is there.
[0011]
[Means for Solving the Problems]
According to the present invention, a pair of static magnetic field generating means that are arranged vertically opposite to each other with the imaging space interposed therebetween and generate a static magnetic field in the imaging space in the vertical direction, and the imaging of the static magnetic field generating means A gradient magnetic field generating means arranged on the space side for generating a gradient magnetic field in the imaging space; and a cable for supplying a current for generating a gradient magnetic field in the gradient magnetic field generating means, A through hole is provided in the central portion for arranging the cable, and the cable guides the cable from the through hole to the outer peripheral portion of the static magnetic field generating means on the side opposite to the imaging space of the static magnetic field generating means. In a magnetic resonance imaging apparatus comprising means ,
The guide means defines two rails arranged below the static magnetic field generating means and a direction in which the rails are arranged, and fixes the rail to the lower side of the static magnetic field generating means. When the cable is bundled by the bracket and inserted from the direction of the through hole, the bracket bundled with the cable is slid and moved on the rail, and the lower side of the static magnetic field generating means A magnetic resonance imaging apparatus is provided.
[0012]
According to the present invention, there is provided a magnetic resonance imaging apparatus, wherein the guide means includes a rail, and the cable is inserted and fixed along the rail .
[0013]
According to the present invention, there is provided a magnetic resonance imaging apparatus comprising means for bundling the plurality of cables when the cable is composed of a plurality of cables.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.
FIG. 1 shows a configuration diagram of a vertical magnetic field type MRI apparatus according to the present invention. 101 and 102 are superconducting magnets for generating a uniform magnetic field in the imaging space, and are provided with a concave gradient magnetic field coil arrangement space on the opposing surface of the coil storage container arranged vertically opposite (101 is the upper side, 102 is the lower side), 103 and 104 are through-holes that penetrate the central part of the superconducting magnet (103 is the upper side, 104 is the lower side), 2 is the subject, 3 is for placing the subject 2 in the imaging space Top plate, 4 is a base for fixing the superconducting magnet to the floor, 501 and 502 are each arranged in the concave arrangement space of the superconducting magnet (101, 102), and a gradient magnetic field coil for adding positional information to the imaging space , 601 and 602 are high-frequency magnetic field coils that irradiate a high-frequency magnetic field to proton atoms of the subject 2 (601 is the upper side, 602 is the lower side), 7 is a high-frequency magnetic field receiving coil that receives the NMR signal generated from the subject 2, Reference numerals 801 and 802 denote gradient magnetic field coils for fixing the gradient magnetic field coils (501 and 502). 901 and 902 are gradient coil coils that are drawn out of the imaging space from the center of the gradient coil through the through holes (103, 104) of the superconducting magnet. (901 is the upper side, 902 is the lower side). Further, 15 is a transmission / reception system for converting the NMR signal detected by the high-frequency magnetic field receiving coil 7 into an audio frequency signal, and 16 is an AD for A / D converting the NMR signal converted into the audio frequency signal into a digital signal. A converter 17 is an operation control unit that performs necessary processing on the A / D converted digital signal and reconstructs the image, and 18 is a gradient magnetic field power source. The motion control unit 18 also tilts a predetermined voltage and current value via a cable at an appropriate timing by the gradient magnetic field power source 18 in order to generate a gradient magnetic field for adding position information necessary for imaging to the NMR signal. Control is also applied to the magnetic field coil.
[0015]
The MRI apparatus according to the embodiment of the present invention is further configured as follows to achieve the object of the present invention. That is, 10 and 11 are brackets for bundling and inserting the cable (902) of the lower gradient coil, 10 being placed in the through hole (104) when inserted, and 11 being the lower It is arrange | positioned under a side superconducting magnet. The cable (902) of the lower gradient coil is inserted and bundled into the metal fittings (10, 11) having a hollow portion therein, and is appropriately inserted by inserting the metal fittings (10, 11) into the through holes. Placed in position. 12 and 13 are two rails arranged on the lower side of the lower superconducting magnet (102), and when the metal fitting (11) bundled with the cable (902) is inserted from the direction of the through hole (104), The metal fitting (11) is slid and moved on the rail, and the cable (902) is preferably arranged below the lower superconducting magnet (102). 14 is a metal fitting for defining the direction in which the rails (12, 13) are arranged and fixing the rails (12, 13) to the lower side of the lower superconducting magnet (102).
[0016]
On the other hand, the gradient magnetic field cable (901) passing through the upper side of the upper superconducting magnet 101 has a space for the operator to climb up and fix it on the upper superconducting magnet 101. The magnetic field cable (901) is fixed on the upper superconducting magnet (101).
[0017]
Next, FIG. 2 shows an enlarged view of a mechanism for fixing the cable (902) of the lower gradient coil in the embodiment of the present invention.
102 is a lower superconducting magnet, 802 is a lower gradient coil support, 902 is a lower gradient coil cable, 10, 11 and 14 are metal fittings, and 12 and 13 are rails. However, the A side indicated by the arrow in FIG. 2 is the same as the A side indicated by the arrow in FIG.
[0018]
The procedure for assembling the mechanism for fixing the cable (902) of the lower gradient coil is as follows. First, the gradient coil support base 802 is attached to the lower superconducting magnet 102. The gradient coil support 802 is provided with fixing holes (not shown) for fixing the rails (12, 13). The rails (12, 13) are fixed to the fixing holes with bolts and nuts. Is done. The rails (12, 13) are arranged in the direction of the metal fitting 14, and are fixed to the lower side of the outermost peripheral portion of the lower superconducting magnet 102 by the metal fitting 14.
[0019]
On the other hand, a cable (902) of the gradient coil is drawn out from the gradient coil, but they are bundled in advance by the metal fittings (10, 11). (However, the number of gradient coil coils (902) consists of three types of gradient magnetic fields that are required for the MRI apparatus, which generally correspond to three-dimensional coordinates of X, Y, Z. There are three types, and the number of gradient coil cables (902) is 6 in total, including input and output.) And gradient coil, gradient coil cable (902), gradient coil cable ( The brackets (10, 11) bundled with the 902) are integrally installed at a predetermined position. At this time, the brackets (10, 11) bundled with the cables (902) are mounted on the gradient coil support (802). The side and rails (12, 13) are arranged to slide.
[0020]
The metal fitting (11) is arranged so as to change the direction of a narrow space from the side surface of the gradient coil support (802) onto the rails (12, 13). The metal fittings (11) are composed of a plurality of pieces so that they can be converted, and each of them is sufficiently short in the insertion direction. Further, the shape of the metal fitting (11) is such that the opposing surfaces of the metal fitting (11) can mesh with each other so that the rail (12, 13) can be suitably slid. In the present embodiment, the cross-sectional shape of the two rails (12, 13) is circular, and two semicircular grooves are provided on the surface of the metal fitting (11) opposite to this, and the interval between them is Is the same as the distance between the two rails (12, 13), and the radius is the same as or slightly larger than the rail radius.
[0021]
According to the above embodiment, even if the operator does not enter the lower superconducting magnet (102), the lower gradient coil cable (902) is placed below the lower superconducting magnet (102). A vertical magnetic field MRI apparatus that can arrange the cable (902) of the lower gradient magnetic field coil in a narrow space under the magnet while the height of the imaging space is an appropriate height. Can be provided. The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
[0022]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a vertical magnetic field MRI apparatus in which a cable for supplying a current to the lower gradient coil can be suitably arranged in a narrow space under the magnet.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a vertical magnetic field type MRI apparatus according to the present invention.
FIG. 2 is an enlarged view of a mechanism for fixing a cable of a lower gradient coil.
FIG. 3 is a wiring array of gradient coil coils in a conventional vertical magnetic field type MRI apparatus.
[Explanation of symbols]
10, 11, 14 ... metal fittings
12, 13 ... Rail

Claims (1)

A pair of static magnetic field generating means for vertically generating a static magnetic field in the imaging space, and disposed on the imaging space side of the static magnetic field generating means; A gradient magnetic field generating means for generating a gradient magnetic field in the imaging space; and a cable for supplying an electric current for generating a gradient magnetic field in the gradient magnetic field generating means, wherein the cable is provided at the center of the static magnetic field generating means through holes provided for arranging the magnetic resonance of the cable, with a guide for guiding means to the outer peripheral portion of the static magnetic field generating means in the imaging space opposite of the static magnetic field generating means from the through-hole In the imaging device,
The guide means defines two rails arranged below the static magnetic field generating means and a direction in which the rails are arranged, and fixes the rail to the lower side of the static magnetic field generating means. When the cable is bundled by the bracket and inserted from the direction of the through hole, the bracket bundled with the cable is slid and moved on the rail, and the lower side of the static magnetic field generating means A magnetic resonance imaging apparatus, wherein

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